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<concept id="GUID-215935B4-8AA8-4A87-B70F-E43ADB70B1D2" xml:lang="en"><title>Constructing
the UI controller in traditional architecture</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The call on the first phase constructor method of the UI controller
occurs in the <xref href="GUID-935C59EE-AD66-33FE-987B-BD97F5147CC1.dita"><apiname>CAknDocument</apiname></xref>-derived class of application.
For more information, see <xref href="GUID-07D2ED79-90B2-4ABC-A61F-108DAEE21955.dita">Implementing
framework requirements</xref>.</p>
<p>The methods you need to implement for your <xref href="GUID-6F2BAB12-6273-3314-B9F1-9AA08403F5EF.dita"><apiname>CAknAppUI</apiname></xref>-derived
UI controller are as follows:</p>
<ul>
<li><p>C++ default constructor, which cannot contain any code that
might leave. A common implementation is:</p>
<itemgroup>
<codeblock id="GUID-277B178E-63D3-4201-A9EB-041E597CA455" xml:space="preserve">CMyAppAppUi::CMyAppAppUi()
    {
    // No implementation required
    }</codeblock>
<p>The class declaration for this constructor in the class header file
needs to be public to support the construction method required.</p>
</itemgroup>
</li>
<li><p>Symbian 2nd phase constructor with code that might leave.
A common implementation is:</p>
<itemgroup>
<codeblock id="GUID-D6CB5AB6-012E-43ED-A25A-A903532BB650" xml:space="preserve">
void CMyAppAppUi::ConstructL()
    {
    // Initialise app UI with skins enabled.
    BaseConstructL(EAknEnableSkin);

    // Create view object
    iAppView = CMyAppView::NewL( ClientRect() );

    }
</codeblock>
<p><xref href="GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E.dita#GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E/GUID-7C3B4A9B-7829-39F7-8F52-AFCA30783C46"><apiname>CEikAppUi::ConstructL()</apiname></xref> completes the construction
of the object. It is a public constructor in the header file.</p>
<p><xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita#GUID-77329067-34D9-3698-B764-294535E660EB/GUID-04316C10-2C88-3EA5-AE37-48E78C7B5064"><apiname>CAknAppUi::BaseConstructL()</apiname></xref> initializes the application
with standard Symbian platform UI application values, including the color
scheme look and feel for all UI controls, the status pane, and the <xref href="GUID-5918ED8A-B26B-41A0-94A6-AB6D51BF80A1.dita">menus</xref> . <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita#GUID-77329067-34D9-3698-B764-294535E660EB/GUID-04316C10-2C88-3EA5-AE37-48E78C7B5064"><apiname>CAknAppUi::BaseConstructL()</apiname></xref> can accept flags enumerated in <xref href="GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E.dita"><apiname>CEikAppUi</apiname></xref> and <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita"><apiname>CAknAppUi</apiname></xref>.
In particular, the <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita#GUID-77329067-34D9-3698-B764-294535E660EB/GUID-B0D8013D-5D6F-3A55-9601-A49614B4AAC8"><apiname>CAknAppUi::EAknEnableSkin()</apiname></xref> flag enables <xref href="GUID-A1DBE03F-728E-4F31-BE74-5BDA3906C8DD.dita">themes</xref> in the application.</p>
<p><parmname>iAppView = CMyAppView::NewL( ClientRect() )</parmname> where <parmname>NewL</parmname> is
a two-phase constructor for the view. The view object is owned by the UI controller
and must be included in the class destructor to free the reserved resources.</p>
</itemgroup>
</li>
</ul>
<p>The UI controller automatically supports <xref href="GUID-B02C762B-C452-4184-ABEA-4753E6CD47D2.dita">scalability</xref>.</p>
<p>You must implement other methods to support <xref href="GUID-E402616A-7ED8-45AC-B836-99C3A3760B33.dita">key
event handling</xref>, <xref href="GUID-4941C035-C359-4968-9BD5-31F44EE5F810.dita">command
handling</xref>, <xref href="GUID-DD15F24B-0786-4531-A6C5-A5E70EBE2732.dita">layout
change support</xref>, and other possible <xref href="GUID-EF7FF39E-929F-4767-B475-5D582D37BB32.dita">events</xref>,
as well as overriding default <xref href="GUID-A4F3738C-CBFD-4151-9132-26FE05966715.dita">control
pane</xref> and status pane behavior.</p>
</conbody></concept>